Fix S6802 FN: Lambdas in loop without a direct block are not reported

[sebastien-marichal]

Lambdas inside a loop without a direct block as a child are not reported by S6802:

@foreach (var item in Buttons.Where(x => x.Id == "idToFind"))
    @if (item.Id == "idToFind")
    {
        <button @onclick="(e) => Reset(e)">Reset #3</button> @* False Negative *@
    }

This is due to the implementation checking if the lambda is inside a direct descendant block of the loop:

private static bool IsWithinLoopBody(SyntaxNode node) =>
    node.AncestorsAndSelf().Any(x => x is BlockSyntax && x.Parent is ForStatementSyntax or ForEachStatementSyntax or WhileStatementSyntax or DoStatementSyntax);

Repros have been added in #8387.